Double-unit trains increase passenger capacity but also increase energy consumption. Therefore, research about the aerodynamic resistance of a double-unit train is of great importance to save energy. In this study, a commercial long-marshalling high-speed train and 8 kinds of double-unit trains are used to investigate the effect of the gap length on aerodynamic resistance. The results show that the aerodynamic resistance of the double-unit train is 8.5%-12.9% larger than that of the long-marshalling train. It is the tail car (CC1 car) of the first single-unit train and the head car (CC2 car) of the second single-unit train that lead to the difference in resistance. For the double-unit trains with different gap length, the resistance increases incrementally with the gap length, which is also mainly caused by the CC1 and CC2 cars. With increases to the gap length (starting from 0 mm), the resistance of the CC1 car increases with the cremental increases in the gap lengths. The resistance of the CC2 car also gradually increases when the gap lengths become larger. The resistance of the CC1 car with a gap length of 0 mm is slightly greater than that with 25 mm.

双列火车增加了载客量，但同时也增加了能耗。因此，研究双组列车的空气动力阻力对于节约能源具有重要意义。在这项研究中，商业长编组高速列车和8种双单元列车被用来研究间隙长度对空气动力阻力的影响。结果表明，双排列车的空气动力阻力比长编组列车的空气动力阻力大8.5％-12.9％。导致电阻差异的是第一单列火车的尾车（CC1轿厢）和第二单列火车的头车（CC2轿厢）。对于间隙长度不同的双组列车，阻力随间隙长度的增加而增加，这也主要是由CC1和CC2车厢引起的。随着间隙长度的增加（从0毫米开始），CC1车的电阻会随着间隙长度的增加而增加。当间隙长度变大时，CC2车的电阻也逐渐增加。间隙长度为0 mm的CC1车的电阻略大于25 mm的电阻。